1. Field of the Invention
The present invention relates to a mechanism for controlling a dual transmission zero turning radius vehicle.
2. Prior Art
Dual transmission vehicles having a zero turning radius capability are well known. Such vehicles are frequently used, for example, as riding lawn mowers.
A conventional control arrangement for dual transmission vehicles employs two separate operator-controlled joysticks connected to the respective transmissions for controlling the speed and/or direction of drive wheels joined to the transmissions. Such mechanisms can be difficult and awkward to manipulate. Accordingly, efforts have been made to control dual transmission vehicles for zero turning radius purposes by associating transmission control with a conventional steering wheel. An example of such an arrangement is disclosed in U.S. Pat. No. 5,042,238.
The present invention represents an improved mechanism for controlling a dual transmission zero turning radius vehicle. A single control element, preferably in the form of a steering wheel, is joined through a rack and pinion arrangement to selectively rectilinearly move a first plate back and forth in a first direction. The plate""s provided with a profiled slot having a major axis extending in the direction of plate movement. The first plate is positioned on overlaying relationship with a second plate operatively connected to a conventional foot-controlled pedal of the type which is pivoted about a neutral position to cause the vehicle to accelerate, either forwardly or in reverse, depending on the direction in which the pedal is pivoted. When the pedal is actuated, the second plate is moved rectilinearly in a direction substantially perpendicular to the direction of movement of the first plate. The second plate is provided with a pair of parallel slots oriented in the direction of the second plate""s movement, the slots communicating with the profiled slot of the first plate.
A pair of biased connecting rods is joined at first ends thereof to respective transmissions. The opposite ends of the rods are provided with protrusions which project through the single profiled slot provided in the first plate and through respective ones of the slots formed in the second plate. Depending on the position of the protrusions relative to the slots through which they project, the vehicle""s drive wheels are controlled in speed and direction.